Peculiarities in the electronic structure of vanadium metal (original) (raw)
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Electronic correlations in vanadium revealed by electron-positron annihilation measurements
Physical Review B, 2017
The electronic structure of vanadium measured by Angular Correlation of electron-positron Annihilation Radiation (ACAR) is compared with the predictions of the combined Density Functional and Dynamical Mean-Field Theory (DMFT). Reconstructing the momentum density from five 2D projections we were able to determine the full Fermi surface and found excellent agreement with the DMFT calculations. In particular, we show that the local, dynamic self-energy corrections contribute to the anisotropy of the momentum density and need to be included to explain the experimental results.
physica status solidi (a), 2001
The electronic structure of vanadium dioxide in its monoclinic and tetragonal (rutile) phase are calculated using the ab initio FP-LAPW method. Both VO 2 phases yield very similar band structures and densities of states (DOS) as expected from their structural similarity. A comparison of theoretical band dispersions of tetragonal VO 2 with recent angular resolved photoemission data yields very good agreement, which confirms the reliability of the FP-LAPW method to account for electronic dispersions in the present systems. The calculations yield metallic behavior for both VO 2 phases in contrast to experimental findings of the monoclinic phase being a small gap semiconductor. This discrepancy is explained by missing correlation contributions in the density functional theory (DFT) scheme used in the calculations. The DOS curves of the bulk systems are compared with the DOS of VO 2 (011) surface clusters obtained by DFT calculations and yield very close similarity in the O 2p band region without surface specific features which remains to be explained.
The fermi surface properties of vanadium
Physica B: Condensed Matter, 1992
In this paper we report calculations of the Fermi surface of vanadium. The calculations are performed self-consistently using the linear muffin tin orbital (LMTO) method in the atomic sphere approximation (ASA). The extremal areas for different Fermi surface orbits are calculated in the local density approximation for various exchange correlation potentials. The results are compared with the available experimental results as well as with some of the earlier calculations for vanadium. 0921-4526/92/$05.00
Electron Optical Studies of Vanadium Compounds
1988
After an introductory chapter on the theory of electron microscopy, which was the predominant technique used in this study, the work described in this thesis was divided into two parts, namely, the thermal decomposition of ammonium metavanadate and the use of vanadium pentoxide as a support for rhodium catalyst. The thermal decomposition of ammonium metavanadate, up to 400
EPL (Europhysics Letters), 2017
Theoretically, various physical properties of AV2O4 (A=Zn, Cd and Mg) spinels have been extensively studied for last 15 years. Besides of this, no systematic comparative study has been done for these compounds, where the material specific parameters are used. Here, we report the comparative electronic behaviour of these spinels by using a combination of density functional theory and dynamical mean-field theory, where the self-consistent calculated Coulomb interaction U and Hund's coupling J (determined by Yukawa screening λ) are used. The main features, such as insulating band gaps (Eg), degree of itinerancy of V 3d electrons and position of lower Hubbard band are observed for these parameters in these spinels. The calculated values of Eg for ZnV2O4, CdV2O4 and MgV2O4 are found to be ∼0.9 eV, ∼0.95 eV and ∼1.15 eV, respectively, where the values of Eg are close to experiment for ZnV2O4 and MgV2O4. The position of lower Hubbard band are observed around ∼-1.05 eV, ∼-1.25 eV and ∼-1.15 eV for ZnV2O4, CdV2O4 and MgV2O4, respectively, which are also in good agreement with the experimental data for ZnV2O4. The order of average impurity hybridization function of V site are found to be ZnV2O4>MgV2O4>CdV2O4. Hence, the degree of localization of V 3d electrons is largest for CdV2O4 and smallest for ZnV2O4, which is in accordance with our earlier results. Hence, present work shows the importance of material specific parameters to understand the comparative electronic behaviour of these compounds.
Rotationally resolved photoelectron spectroscopy of the vanadium dimer
Chemical Physics, 1996
Results of calculations of the rotationally resolved photoelectron spectra of the V: ground state obtained by two-color excitation via the A %I, + X3x, system are reported and compared with recent pulsed-field-ionization zero-kinetic-energy measurements of these spectra. Agreement between the measured and calculated spectra is very encouraging. Both illustrate that the spin-orbit interaction plays an important role in photoionization of the A 'n, state of V2 leading to the X 42, state of V:. Striking differences are seen in the ion rotational distributions for ionization via the A3rIl, and A 3lI2U spin-orbit components.
Inorganic Chemistry, 2010
The molecular geometries of VCl 2 and VCl 3 have been determined by computations and gas-phase electron diffraction (ED). The ED study is a reinvestigation of the previously published analysis for VCl 2 . The structure of the vanadium dichloride dimer has also been calculated. According to our joint ED and computational study, the evaporation of a solid sample of VCl 2 resulted in about 66% vanadium trichloride and 34% vanadium dichloride in the vapor. Vanadium dichloride is unambiguously linear in its 4 Σ g þ ground electronic state. For VCl 3 , all computations yielded a Jahn-Tellerdistorted ground-state structure of C 2v symmetry. However, it lies merely less than 3 kJ/mol lower than the 3 E 00 state (D 3h symmetry). Due to the dynamic nature of the Jahn-Teller effect in this case, rigorous distinction cannot be made between the planar models of either D 3h symmetry or C 2v symmetry for the equilibrium structure of VCl 3 . Furthermore, the presence of several low-lying excited electronic states of VCl 3 is expected in the high-temperature vapor. To our knowledge, this is the first experimental and computational study of the VCl 3 molecule.
The Journal of Chemical Physics, 2014
Six electronic states (X 4 − , A 4 , B 4 , 2 , 2 , 2 + ) of the vanadium monochloride cation (VCl + ) are described using large basis set coupled cluster theory. For the two lowest quartet states (X 4 − and A 4 ), a focal point analysis (FPA) approach was used that conjoined a correlationconsistent family of basis sets up to aug-cc-pwCV5Z-DK with high-order coupled cluster theory through pentuple (CCSDTQP) excitations. FPA adiabatic excitation energies (T 0 ) and spectroscopic constants (r e , r 0 , B e , B 0 ,D e , H e , ω e , v 0 , α e , ω e x e ) were extrapolated to the valence complete basis set Douglas-Kroll (DK) aug-cc-pV∞Z-DK CCSDT level of theory, and additional treatments accounted for higher-order valence electron correlation, core correlation, and spin-orbit coupling. Due to the delicate interplay between dynamical and static electronic correlation, single reference coupled cluster theory is able to provide the correct ground electronic state (X 4 − ), while multireference configuration interaction theory cannot. Perturbations from the first-and second-order spin orbit coupling of low-lying states with quartet spin multiplicity reveal an immensely complex rotational spectrum relative to the isovalent species VO, VS, and TiCl. Computational data on the doublet manifold suggest that the lowest-lying doublet state ( 2 ) has a T e of ∼11 200 cm −1 . Overall, this study shows that laboratory and theoretical rotational spectroscopists must work more closely in tandem to better understand the bonding and structure of molecules containing transition metals.
Structural Phase Transition of Vanadium at 69 GPa
Physical Review Letters, 2007
A phase transition was observed at 63-69 GPa and room temperature in vanadium with synchrotron x-ray diffraction. The transition is characterized as a rhombohedral lattice distortion of the body-centeredcubic vanadium without a discontinuity in the pressure-volume data, thus representing a novel type of transition that has never been observed in elements. Instead of driven by the conventional s-d electronic transition mechanism, the phase transition could be associated with the softening of C 44 trigonal elasticity tensor that originates from the combination of Fermi surface nesting, band Jahn-Teller distortion, and electronic topological transition.